California appears to be on track for another low-turnout election as county clerks and analysts report that mail ballots are trickling in slowly compared with previous election cycles.

Many political observers expected low voter interest this year in a cycle with a governor's race devoid of drama and no U.S. Senate race or high-interest ballot initiative. Primary turnout already hit a record low this year when just one in four registered voters cast ballots in June.

"We are not seeing the same call volume in 2010, the same Web hits and the same number of questions - and that's matching returns," said Neal Kelley, the Orange County registrar of voters and president of California Association of Clerks and Election Officials.

In 2010, the last non-presidential statewide election, 2.9 million vote-by-mail ballots had been returned by this point, according to an analysis by the firm Political Data Inc. This year, that number is just 2.2 million, even though the number of absentee voters has grown by 3 million.

From 2010 to 2014, the number of Los Angeles County voters requesting mail ballots nearly doubled to 1.5 million. About one in six voters have returned their ballots this year compared with more than half in the last election.

These aren't necessarily signs of widespread voter apathy, according to some officials who expect more absentee voters to drop their ballots off at polling stations instead of mailing them. Ballots must be received by Election Day to be counted.

"More and more voters are getting the message that the mail is taking longer," said Kim Alexander, president of the California Voter Foundation.

The secretary of state's office announced Friday that 17.8 million Californians are registered to vote, with registered Democrats holding a 15-point lead over Republicans.

California's lowest general-election turnout in the past century was in 2002, when half of registered voters cast ballots.

"Whether (this year) is going to go below that, it's hard to say, but it's not going to be much higher," said Eric McGhee, a research fellow with the Public Policy Institute of California.

Former President Bill Clinton visited the state this week on behalf of vulnerable Democratic congressional candidates and urged Californians to vote, saying it is the solution to intense political gridlock and polarization in Washington. Low turnout elections generally help Republican candidates, but this year's lack of interest doesn't appear to be helping the GOP regain statewide office.

"In every statewide candidate race, the Democrat is ahead and likely to still win. That's how blue California is," Field Poll director Mark DiCamillo said.

Where low turnout can tilt the scales is in tightly contested state legislative and congressional races. Freshman Democrats face tight contests to keep their U.S. House seats in San Diego, Ventura County and a suburban Sacramento district.

Those races could also end up boosting voter participation in their districts come Election Day.